Bioaccumulation of Polychlorinated Biphenyls from Sediments to Aquatic Insects and Tree Swallow Eggs and Nestlings in Saginaw Bay, Michigan, Usa

Sediments in the Saginaw Bay region of the Great Lakes contain concentrations of polychlorinated biphenyls (PCBs) that may adversely affect biotic species in various trophic levels. In this study we collected and analyzed sediments, benthic invertebrates, tree swallow eggs, and nestlings to evaluate linkages between PCBs in sediments and at various trophic levels in the Saginaw River, Michigan, USA. Our results indicate that patterns of relative concentrations of PCB congeners change with trophic level, specifically from sediment to invertebrates and from tree swallow eggs to nestlings. However, if biota–sediment accumulation factor (BSAF) values are based on only the nonand mono-ortho-substituted PCB congeners or 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TEq), calculated BSAF values are close to those predicted by fugacity theory. The use of site-specific BSAF values and reference doses for toxic effects in wildlife can be used to derive sediment quality criteria (SQC) that are protective of wildlife at the top of the sediment-based food chain. The threshold concentration of TEq in sediments that would protect sensitive avian species at the same trophic level as tree swallows was calculated to be 1.5 3 1021 TEq/g total organic carbon. Based on this value and the BSAF determined for tree swallow nestlings, the hazard quotient for sediments in this area was determined to be 0.7. This indicates that current concentrations of TEq due to PCB congeners in the sediments should be below the threshold for adverse effects on tree swallows. The uncertainty in the concentrations of PCB congeners in the sediments was approximately a factor of 2, which determined the degree of resolution that could be obtained from the observations made in this study. Keywords—Biota–sediment accumulation factor Bioaccumulation Benthic invertebrates Birds Fugacity